KONGL. SV. VET. AKADEMIENS HANDLINGAE. BAND 26. N:0 2. 103 



narrow, with a row of large granules, formed by the continuation of the costse. Costee 3 to 4 in 

 0,01 mm. alternating with double rows of coarse puncta. Lunulse none or narrow. Ocelli forming 

 a marginal band, and, besides, a band along the furrows or lunulse. 



This species, which is intermediate between D. Crahro and D. vagabunda, differs from D. 

 Crabro in nothing but the double rows of ocelli. The form of the valve is variable, usually 

 elliptical, but in some specimens panduriform. The lunulse are indistinct in some forms, narrow in 

 others. It would be admissible to group the forms of this species together with the forms of D. 

 Grabro. The var. Kinheriana and galapagensis are analogous to the Pandura-series, the var. lata 

 to the separabilis-series. 



Var. Galapagensis Cl. — V. not constricted, elliptical. L. 0,i2; B. 0,o5 mm. Costse 4 in 

 0,01 mm. alternating with double rows of coarse puncta. Lunulse very narrow. Ocelli forming a 

 marginal and an interior row. — PL II f. 16. 



Marine: Galapagos Islands! 



Var. lata Cl. — V. elliptical, not constricted. L. 0,ii; B. 0,04 8 mm. Costse 4 in 0,oi mm. 

 Lunulse moderately broad. — PL II f. 14. 



Marine: Galapagos Islands! 



The fig. 12 PL CLXXIV in A. S. Atl. represents doubtless a small, but strongly corroded 

 form of D. biseriata. 



80. D. vagabunda Brun (1892). — V. panduriform with tongue-shaped segments. L. 0,i3 

 to 0,17; B. 0,0 6; at the constriction 0,04 3 mm. Central nodule large, quadrate; its horns nearly 

 parallel. Furrows narrow, linear, with a row of large granules. Lunulse very narrow or not di- 

 stinct. Costse 3 to 4 in 0,oi mm., alternating with double rows of coarse puncta. Ocelli forming 

 a marginal band and several oblique or curved rows besides. — Nav. vagabunda Brtjn A. S. Atl. 

 CLXXIV f. 5. Bipl. vag. Icon. n. PL II f. 13, 15. 



Marine: Tamatave (Kinker Coll.)! Fossil: S:ta Monica, S:n Pedro (Kinker CoU.) Calif.! 

 D. vagabunda is a transitional form from D. biseriata to D. gemmatula (var. Beyrichiana). 



81. D. prisca A. S. (1875). — V. slightly constricted, with tongue-shaped or cuneate, 

 obtuse segments. L. O.07 to O.os; B. 0,029 to 0,03 mm., at the constriction 0,02 to 0,027 mm. 

 Central nodule quadrate; its horns parallel and approximate. Furrows narrow, linear, with a row 

 of large puncta. Transverse costse 7 to 8 in 0,oi mm. alternating with double rows of puncta, 

 about 16 in O.oi mm. and ocelli, 4 to 5 in 0,oi mm. — Nav. prisca A. S. Atl. PL XII 

 f. &Q to 68 (69?). 



Marine; Nottingham (Maryland)! Atlantic City, N. Jers. (Grove Coll.), Richmond, Va! 

 always fossil. 



This species is very nearly akin to D. gemmatula from which it differs by the narrow 

 furrows. The exterior stratum with small alternating puncta is usually preserved in D. prisca, 

 but never found on D. gemmatula, which may be a consequence of the state of preservation and 

 preparation. 



82. D. gemmatula Grun. (1875). — V. slightly constricted, with tongue-shaped to broadly 

 cuneate segments. L. 0,07 to 0,15; B. 0,o33 to 0,062; at the constr. 0,027 to 0,o5 mm. Central 

 nodule large; its horns almost parallel. Furrows usually broad, and somewhat dilated in the 

 middle, with a row of large puncta. Costse 5 to 7 in 0,oi mm. alternating with rows of more or 

 less numerous, large ocelli. 



Var. hungarica Cl. — V. moderately constricted. L. 0,08; B. 0,025; at the constr. 0,oi8 

 mm. Ocelli forming one row along the margin and one along furrows. 

 Marine: Szakal, Hungary, fossil! 

 Akin to Nav. expedita A. S. (Atl. LXIX f. 6) from Moron. 



